Hook assembly for chain tensioners

ABSTRACT

Aspects of the invention are directed to an apparatus that may be used as a chain tensioner. The apparatus comprises an attachment element, such as a hook, that is rotatably coupled to a locking plate. In use, the apparatus is operative to take on a plurality of locked states and an unlocked state. Each of the plurality of locked states is characterized by the locking plate being pressed into a cavity of a locking body in a manner that prevents the locking body, and, by extension, the attachment element from rotating. The unlocked state is characterized by the locking plate being outside the cavity, and thereby free to rotate. The attachment element is therefore capable of being swiveled between, and locked into, multiple orientations.

FIELD OF THE INVENTION

The present invention relates generally to load-engaging elements, and,more particularly, to chain tensioners for use in securing cargo fortransport.

BACKGROUND OF THE INVENTION

Chain tensioners (sometimes called “tie down tensioners”) are commonlyused to secure cargo during transport. A chain tensioner will typicallycomprise an apparatus with a hook at one end and a means for attaching achain at the other. The chain may be attached to the cargo, while thehook may be attached to a tie-down ring on an aircraft or other form oftransport. After the chain is initially attached between the chaintensioner and the cargo, a tensioning wheel on the chain tensioner maybe rotated to effectively reduce the length of the chain tensioner, andthereby increase the tension on the chain. Later, the chain may bequickly released by manipulating a release handle on one side of thechain tensioner. Such chain tensioners are available from, for example,Davis Aircraft Products Co. (Bohemia, N.Y., USA), as well as others.

When utilizing a chain tensioner to restrain cargo, it is generallypreferred that the release handle face upward so that the operator canquickly ascertain its state and avoid unintended releases. In November2011, the U.S. Department of Defense (DOD) reinforced this preference bypublishing Detail Specification MIL-DTL-25949H, which is herebyincorporated by reference herein. In this Specification, the DODrequests a new chain tensioner design with the ability to rotate itshook relative to the remainder of the device. More specifically, therequested chain tensioner must have the capability of swiveling andlocking the hook into two positions 180-degrees from one another. TheSpecification further requires that the hook shall be capable ofrotating in both the clockwise and counterclockwise directions, and thatno tools shall be required to rotate and lock the hook into the neworientations.

For the foregoing reasons, there is a need for new chain tensionerdesigns that incorporate hook connection assemblies capable of allowinga hook to be swiveled between, and locked into, multiple orientations.

SUMMARY OF THE INVENTION

Embodiments of the present invention address the above-identified needsby providing chain tensioner designs that incorporate an attachmentelement (e.g., hook) capable of being swiveled between, and locked into,multiple orientations.

Aspects of the invention are directed to an apparatus comprising: aframe, a locking body, a threaded receiver, a locking plate, a biasingelement, an attachment element, and a threaded shaft. The locking bodyis fixed in the frame, and defines a cavity and an aperture therein, theaperture being in communication with the cavity. Moreover, the threadedreceiver passes through the aperture, at least partially occupies thecavity, and is free to rotate. The locking plate defines a mating slotand has a shape that prevents the locking plate from rotating within thecavity when the locking plate is inserted into the cavity. The biasingelement is in contact with the locking plate. Lastly, the threaded shaftextends in a longitudinal direction from the attachment element throughthe threaded receiver and the mating slot, and is shaped so as tocooperate with the mating slot to prevent the threaded shaft fromrotating independently of the locking plate while still beingtranslatable in the longitudinal direction therethrough. The apparatusis operative to take on a plurality of locked states and an unlockedstate, each of the plurality of locked states characterized by thelocking plate being pressed into the cavity by the biasing element andthereby prevented from rotating by the locking body, and the unlockedstate characterized by the locking plate being outside the cavity andthereby free to rotate. The unlocked state can be achieved from arespective one of the plurality of locked states by manually pressingthe threaded receiver against the locking plate so as to translate thelocking plate out of the cavity counter to the bias of the biasingelement.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood with regard to the followingdescription, appended claims, and accompanying drawings where:

FIGS. 1 and 2 show front and rear perspective views, respectively, of anapparatus 100 in accordance with an illustrative embodiment of theinvention;

FIG. 3 shows an exploded side perspective view of the hook assembly inthe apparatus 100, in accordance with an illustrative embodiment of theinvention;

FIG. 4 shows a bottom perspective view of several elements within theFIG. 3 hook assembly;

FIGS. 5-7 show partially cutaway elevational views of a portion of theFIG. 3 hook assembly in locked and unlocked states;

FIG. 8 shows a partially cutaway perspective view of a portion of theFIG. 3 assembly relating to the tension wheel locking mechanism;

FIG. 9 shows a rear perspective view of the chain capture assembly inthe apparatus 100, in accordance with an illustrative embodiment of theinvention;

FIG. 10 shows a front exploded perspective view of elements in the FIG.9 chain capture assembly; and

FIGS. 11-13 show partially broken side elevational views of the FIG. 9chain capture assembly and chain with the chain capture assembly in thelocked, unlocked, and open configurations, respectively.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be described with reference to illustrativeembodiments. For this reason, numerous modifications can be made tothese embodiments and the results will still come within the scope ofthe invention. No limitations with respect to the specific embodimentsdescribed herein are intended or should be inferred.

As used herein, the term “about,” when used to modify a length, shallmean within 15 percent of the recited length. In addition, as usedherein, pairs of sidewalls, surfaces, or edges that are “opposed,”“parallel,” or “oppositely facing” run parallel to each other within tendegrees.

FIGS. 1 and 2 show front and rear perspective views, respectively, of anapparatus 100 in accordance with an illustrative embodiment of theinvention. The apparatus may be conceptually separated into twoportions, which are mated together by a u-shaped frame 102 defining apair of parallel sidewalls 103. At the top of the apparatus 100 (asoriented in FIGS. 1 and 2), a hook assembly 104 provides a hook 106 anda threaded shaft 108, which are longitudinally translatable relative tothe frame 102 in response to the rotation of a tensioning wheel 110. Atthe bottom of the apparatus, a chain capture assembly 112 provides ameans for releasably attaching a chain 114 to the apparatus 100.

So configured, the apparatus 100 may be utilized as a chain tensionerdevice to aid in securing cargo for transport in an aircraft or othermode of transport. Cargo that is attached to the chain 114, for example,can be secured for transport by attaching the hook 106 at one end of theapparatus 100 to a tie-down ring, and then attaching the chain 114 tothe apparatus 100 at the other end. The apparatus thereby becomes abridge between the tie-down ring and the chain 114. The tensioning wheel110 may subsequently be rotated to obtain the desired tension across thechain 106 and the apparatus 100. It is contemplated that embodiments inaccordance with aspects of the invention would be capable of applyingtensions in excess of 300 pounds. Once the cargo is successfullytransported, the chain can be quickly disconnected via a release handle904.

Each of the hook assembly 104 and the chain capture assembly 112comprises novel and non-obvious aspects, and each portion is nowaddressed in detail. Embodiments in accordance with aspects of theinvention may comprise elements of both portions, or may only compriseaspects of one of the two portions.

I. Hook Assembly

FIG. 3 shows an exploded side perspective view of the hook assembly 104in the apparatus 100, in accordance with an illustrative embodiment ofthe invention. In addition to the frame 102, the hook 106, the threadedshaft 108, and the tensioning wheel 110, the hook assembly 104 furthercomprises: a retaining ring 118, a locking body 120, a threaded receiver122, a locking plate 124, and a biasing element 126. The hook 106comprises a spring-loaded keeper 128. The threaded shaft 108, in turn,attaches to the base of the hook 106 and extends in the longitudinaldirection therefrom. The threaded shaft 108 defines two differentprofiles along its length. An upper portion of the threaded shaftproximate to the hook 106 is defined by an externally threaded cylinder130. Further down the threaded shaft 108, the threaded shaft 108 isdefined by the externally threaded cylinder 130 with a pair ofoppositely facing flat surfaces 132. Near the bottom of the threadedshaft, a pin 134 passes through the threaded shaft 108 to stop thethreaded shaft 108 from being overly extended.

The threaded receiver 122 defines an upper cylindrical portion 136 and alower protruding lip 138 that surround a threaded passageway 140. At thesame time, the locking body 120 defines a cavity 142 and an aperture 144that is in communication with the cavity 142. When assembled, the lowerprotruding lip 138 of the threaded receiver 122 occupies the cavity 142,while the upper cylindrical portion 136 passes through the aperture 144.After so doing, the upper cylindrical portion 136 further passes througha lower opening 146 in the frame 102 before ultimately engaging a shapedopening 148 in the tensioning wheel 110. Where the upper cylindricalportion 136 engages the shaped opening 148, the upper cylindricalportion 136 defines a pair of outside flat surfaces 150 that match theshape of the shaped opening 148. Above the tensioning wheel 110, theretaining ring 118 clips onto the upper cylindrical portion at a groove152. The tensioning wheel 110 and the threaded receiver 122 are therebyboth rotationally and translatably coupled to one another. That is,rotating the tensioning wheel 110 causes the threaded receiver 122 toalso rotate. Moving the tensioning wheel 110 up and down along thelongitudinal axis causes the threaded receiver 122 to also move up anddown along the same axis.

The threaded passageway 140 in the threaded receiver 122 threadablyengages the threaded shaft 108. After passing through the threadedreceiver 122, the threaded shaft 108 further extends through a matingslot 154 in the locking plate 124 and through the biasing element 126.The biasing element 126 presses the locking plate 124 against thethreaded receiver 122. In the present illustrative embodiment, thebiasing element 126 defines a leaf spring in contact with the lockingplate 124, but this particular arrangement is not intended as beinglimiting. A tensioning wheel locking mechanism 156 is also visible on anoutside face of the locking body 120, and is further detailed below.

In the present illustrative embodiment, the locking body 120 is fixatedin the frame 102 by four roll pins 158 that pass through frame apertures160 in the frame 102 and engage complementary holes 162 in the lockingbody 120. The biasing element 126 is fixated to the frame 102 by twobolts 164 that pass through bolt openings 166 in the frame 102 whilesimultaneously passing through the biasing element 126. The bolts aresecured by nuts. 168

The tensioning wheel 110, the locking body 120, the threaded receiver122, the locking plate 124, and the biasing element 126 cooperate toallow the hook 106 to be both translated inward and outward along thelongitudinal axis of the apparatus 100, as well as swiveled between, andlocked into, multiple orientations relative to the frame 102. FIG. 4shows an exploded bottom perspective view of these elements so thatadditional aspects that lend to this functionality may be more easilyappreciated.

It will be noted, for example, that the locking body 120 and the lockingplate 124 are dimensionally related to one another. In the presentillustrative embodiment, the cavity 142 in the locking body 120 isrectangular and defines a pair of parallel internal sidewalls 170 alongits narrower, width axis. At the same time, the locking plate 124,which, in this example is square, defines two pairs of parallel outsideedges 172, 174. In accordance with aspects of the invention, the pair ofparallel internal sidewalls 170 are spaced apart by a distance aboutequal to the spacing between the two pairs of parallel outside edges172, 174. It is therefore possible to insert the locking plate 124 intothe cavity 142 of the locking body 120 in four different orientations.Once so inserted, the pair of parallel internal sidewalls 170 of thelocking body 120 interact with one of the pairs of parallel outsideedges 172, 174 of the locking plate 124 to prevent the locking plate 124from rotating therein. That is, the locking plate 124 has a shape thatprevents it from rotating within the cavity 142 when the locking plate124 is inserted into the cavity 142.

It will be further appreciated, moreover, that the mating slot 154 hasdimensions that relate to the shape of the threaded shaft 108. Asindicated above, a majority of the threaded shaft 108 defines anexternally threaded cylinder 130 with a pair of oppositely facing flatsurfaces 132. The mating slot 154, in turn, is characterized by a pairof opposed sidewalls 176, which are spaced apart by a distance aboutequal to a spacing between the pair of oppositely facing flat surfaces132. At the same time the mating slot 154 is further characterized by apair of opposite sidewalls 178 spaced apart by a distance greater thanthe maximum diameter of the externally threaded cylinder 130. Configuredin this manner, the threaded shaft 108 is able to be translatedlongitudinally through the mating slot 154, but the threaded shaft 108is not able to rotate inside the mating slot 154 because of interferencebetween the pair of oppositely facing flat surfaces 132 and the pair ofopposed sidewalls 176. Stated another way, the threaded shaft 108 is soshaped as to cooperate with the mating slot 154 to prevent the threadedshaft 108 from rotating independently of the locking plate 124 whilestill being translatable in the longitudinal direction therethrough.

Lastly, it will be noted that the cavity 142 defines several internalshoulders 180 therein. In the present illustrative embodiment, theseinternal shoulders 180 are located at the four corners of therectangular cavity 142.

FIGS. 5-7 show partially cutaway elevational views of the hook assembly104 with the purpose of showing how the elements cooperate to allow thehook orientation to be changed and locked. As will be shown by thissequence of figures, the hook assembly 104 is operative to take on aplurality of locked states and an unlocked state. Each of the pluralityof locked states is characterized by the locking plate 124 being pressedinto the cavity 142 by the biasing element 126 and thereby preventedfrom rotating by the locking body 120 in the manner set forth above.With the locking plate 124 unable to rotate, the threaded shaft 108 andthe hook 106 are likewise unable to rotate about the longitudinal axis.In contrast, the unlocked state is characterized by the locking plate124 being outside the cavity 142 and thereby free to rotate, along withthe threaded shaft 108 and the hook 106.

The present hook assembly 104 is operative to take on four differentlocked states, each of which is characterized by a different orientationof the hook 106 relative to the frame 102. FIG. 5 shows the hookassembly 104 in a representative one of these four locked states. Inthis locked state, the biasing element 126 presses the locking plate 124against the threaded receiver 122 and the internal shoulders 180, and,in response, the protruding lip 138 of the threaded receiver 122 abuts aperimeter 182 of the aperture 144 inside the cavity 142. The lockingplate 124 thereby occupies the cavity 142 of the locking body 120,causing the locking plate 124 to be restricted in rotation. In contrast,the threaded receiver 122 remains free to rotate inside the cavity 142in response to the rotation of the tensioning wheel 110. Rotating thetensioning wheel 110 and the threaded receiver 122 causes the threadedshaft 108 and the hook 106 to be translated along the longitudinal axisof the apparatus 100. The apparatus 100 thereby retains its “tensioning”functionality while in the locked state. Stated another way, thetensioning wheel 110 may be rotated with the apparatus 100 in the lockedstate to cause the hook 106 to move in the longitudinal directionrelative to the frame 102 while maintaining a fixed orientation relativeto the frame 102.

FIG. 6 shows the apparatus 100 in the unlocked state. The unlocked statecan be achieved from one of the locked states by manually pressing thethreaded receiver 122 against the locking plate 124 so as to translatethe locking plate 124 out of the cavity 142 counter to the bias of thebiasing element 126. The manual pressing force may be applied to thetensioning wheel 110 because, as discussed above, the tensioning wheel110 is translatably coupled to the threaded receiver 122. In theunlocked state, the biasing element 126 is compressed and the protrudinglip 138 is in spaced relation to the perimeter 182 of the aperture 144,but still partially occupies the cavity 142. With the locking plate 124outside the locking body 120, the locking plate 124 and,correspondingly, the threaded shaft 108 and the hook 106 may be rotatedrelative to the frame 102. In FIG. 6, it will be observed that, forexample, the hook 106 is rotated by about 45-degrees relative to itsorientation in FIG. 5.

Once the hook 106, the threaded shaft 108, and the locking plate 124have achieved an orientation where the locking plate 124 can bereinserted into the locking body 120 (in the present embodiment, at0-degrees, 90-degrees, 180-degrees, and 270-degrees), the manual forcecan be relieved on the tensioning wheel 110 so as to allow the apparatus100 to return to a locked state in response to the biasing force fromthe biasing element 126. Such a condition is shown in FIG. 7, whichshows the locking plate 124 in an orientation where reinsertion into thecavity 142 of the locking body 120 is allowed, but before the manualdownward force has actually been relieved. The hook 106 can thereby bequickly and easily swiveled between, and locked into, multipleorientations relative to the frame 102 without the use of tools. Theswiveling may occur in either direction (i.e., clockwise orcounterclockwise). In any one of the locked states, moreover, thetensioning function that incorporates the longitudinal translation ofthe hook 106 relative to the frame 102 remains available to the userthrough the rotation of the tensioning wheel 110.

An additional feature of the apparatus 100 is the tensioning wheellocking mechanism 156, briefly mentioned above. The main components ofthe tensioning wheel locking mechanism 156 are best seen in FIG. 4,while the positioning and functioning of the tensioning wheel lockingmechanism 156 in the apparatus 100 are best seen in the partiallycutaway front perspective view in FIG. 8. The tensioning wheel lockingmechanism 156 includes a button 184, a coil spring 186, and a retainingpin 188. The button 184 defines an extension 190 at one end. Theretaining pin 188 fixes the tensioning wheel locking mechanism 156 to anoutside sidewall of the locking body 120 via two tabs 192 with alignedholes. So placed, the coil spring 186 pushes the extension-end of thebutton 184 outward away from the locking body 120 towards a cylindricalsidewall 194 of the tensioning wheel 110. The cylindrical sidewall 194defines a plurality of locking windows 196 arranged along its perimeter.

When the tensioning wheel 110 is turned in a direction that increasestension in the apparatus 100 (in this embodiment, in thecounter-clockwise direction), the extension 190 on the button 184continuously ratchets into and out of the locking windows 196 as theymove past. A user may therefore increase tension without attention tothe tensioning wheel locking mechanism 156. On the other hand, once agiven tension is achieved, the button 184 interferes with the tensioningwheel 110 being turned in the opposite direction. That is, the extension190 sits within one of the locking windows 196 and will abut against aninside edge of that locking window 196 if the user tries to rotate thetensioning wheel 110 so as to relieve tension (the condition shown inFIG. 8). This locked state may only be defeated by having the usermanually press the button 184 in against the force of the coil spring186 to move the button 184 and its extension 190 out of the way.

The tensioning wheel locking mechanism 156 thereby allows tension to beincreased via the tensioning wheel 110 without interference, butrequires manual intervention in the form of a button press to reducetension via the tensioning wheel 110. This assures that the tension on asecured load is not inadvertently reduced, which may allow the load toshift.

Once understood from the details provided herein, the elements of thehook assembly 104 may be formed utilizing conventional manufacturingtechniques or, in the case of fasteners, springs, and the like, sourcedcommercially. For strength, most of the elements of the apparatus 100preferably comprise a metal such as, but not limited, to steel. Metalmachining is described in W. A. Knight et al., Fundamentals of MetalMachining and Machine Tools, Third Edition, CRC Press, 2005, which ishereby incorporated by reference herein.

The hook assembly 104 lends itself to several modifications. Thesenumerous alternative embodiments will be apparent to one skilled in theart given the teachings herein.

For example, as detailed above, the illustrative apparatus 100 utilizesa geometric relationship between the cavity 142 of the locking body 120and the locking plate 124 that provides four different lockedorientations of the hook 106 relative to the frame 102 with 90-degreeintervals therebetween. Nevertheless, modified geometries allowadditional locked orientations to be designed into an apparatus, asdesired. Use of a hexagonal locking plate in combination with arectangular cavity (like the cavity 142), for example, may allow analternative embodiment of the invention to take on six locked hookorientations with 60-degree intervals. Similarly, an octagonal lockingplate may allow another alternative embodiment of the invention to takeon eight locked geometries with 45-degree intervals. Thus progressivelymore locked orientations may become available as more outside edges areadded to the locking plate. At the same time, other modified geometriesmay allow fewer than four locked orientations. For example, arectangular locking plate in combination with a rectangular cavity mayprovide only two locked hook orientations with 180-degree intervals. Useof a triangular locking plate in combination with a triangular cavity(instead of rectangular) may provide three locked orientations with120-degree intervals. Accordingly, there are a multiplicity of relatedgeometries that may be used for a locking plate and a locking body, andthese alternative embodiments would also come within the scope of theinvention.

Moreover, while the apparatus 100 is described as having a hook 106 atone end, alternative forms of attachment elements may be utilized.Alternative embodiments may utilize, for example, attachment elementssuch as, but not limited to, rings or clevises.

Even further, while the above-described apparatus 100 utilizesparticular fasteners such as the roll pins 158 and the bolts 164, itshould be reinforced that these particular fasteners are merely by wayof illustration, and that other means of fixation may be used in theirplace. In one or more alternative embodiments falling within the scopeof the invention, for example, screws, an adhesive, or joining may beutilized to fixate one or both of the locking body 120 and the biasingelement 126 to the frame 102.

Finally, while the biasing element 126 in the illustrative apparatus 100is in the form of a leaf spring, alternative biasing elements may beutilized. In one or more alternative embodiments, the leaf spring may,for example, be replaced by two double-coil springs that are fixed tothe frame 102 by bolts 164 and function to press upward on the lockingplate 124. Once the substitution is made, overall functionality willremain similar to what was detailed before.

II. Chain Capture Assembly

FIG. 9 shows a rear perspective view of the chain capture assembly 112in the apparatus 100, in accordance with an illustrative embodiment ofthe invention. FIG. 10, moreover, shows a front exploded perspectiveview of the elements in FIG. 9. The chain capture assembly 112comprises: a primary elongate member 900, a secondary elongate member902, the release handle 904, a release handle label plate 906, a firstlocking spring 908, a second locking spring 910, a first spacer 912, asecond spacer 914, a first rotatable member 916, a second rotatablemember 918, a chain keeper member 920, a coil spring 922, a thirdelongate member 924, and a chain capture block 926.

In the present illustrative embodiment, the primary elongate member 900describes a cylinder, which is fixed to the frame 102 by a bolt 928 thatis terminated by a nut 930 (FIG. 1). In spanning between the pair ofparallel sidewalls 103 of the frame 102, the primary elongate member 900passes through: the release handle 904, the first spacer 912, the firstrotatable member 916, the chain keeper member 920, the coil spring 922,the second rotatable member 918, and the second spacer 914. In so doing,the primary elongate member 900 pivotally supports the release handle904, the first and second rotatable members 916, 918, and the chainkeeper member 920. At the same time, the secondary elongate member 902also spans between the pair of parallel sidewalls 103 of the frame 102.In the present illustrative embodiment, the secondary elongate member902 describes a pin that is held in place by cotter pins 932 (FIGS. 1and 2). The secondary elongate member 902 rides in a first shaped guideslot 934 and a second shaped guide slot 936 in the release handle 904.The first and second shaped guide slots 934, 936 are each characterizedby a respective arc 938 with an angled projection 940 at one end.

The first and second rotatable members 916, 918 are disposed in spacedrelation to one another. The first rotatable member 916 defines a firstslot 942 that engages a lower edge 946 of the release handle 904, whilethe second rotatable member 918 defines a second slot 944 that engagesthe same lower edge 946. Configured in this manner, the first and secondrotatable members 916, 918 are pivotally coupled to the release handle904 so that the first and second rotatable members 916, 918 pivot inunison with the release handle 904.

The third elongate member 924 is supported between the first and secondrotatable members 916, 918 via respective holes 948, 950 in the firstand second rotatable members 916, 918. Positioned in this manner, thethird elongate member 924 describes an arc in response to the pivotingof the first and second rotatable members 916, 918. The coil spring 922spans between the chain keeper member 920 and the third elongate member924. This coupling urges the chain keeper member 920 to pivot in unisonwith the first and second rotatable members 916, 918.

The chain capture block 926 is pivotally mounted to the frame 102 viatwo cylindrical bosses 952, 954 that engage matching holes in the pairof parallel sidewalls 103 of the frame 102. In the present non-limitingembodiment, the chain capture block 926 defines a cavity 956 shaped soas to accept two interlocked links of the chain 114. The two links arein substantially normal relation with one another.

Finally, the first and second locking springs 908, 910 span betweencapture holes 958 in the release handle 904 and the secondary elongatemember 902. The first and second locking springs 908, 910 place adownward bias on the release handle 904. This downward bias urges therelease handle 904 in the direction of the chain capture block 926. Therelease handle label plate 906 is riveted to the release handle 904 viarivets 960. The release handle label plate 906 may contain writteninformation such as manufacturer name, part number, date of manufacture,abbreviated instructions for use, any limitations or warnings, and thelike.

In use, the first and second shaped guide slots 934, 936 in the releasehandle 904 cooperate with the secondary elongate member 902 to restrictthe motion of the release handle 904 between three configurations: alocked configuration, an unlocked configuration, and an openconfiguration. These configurations are shown in FIGS. 11-13. Moreparticularly, FIGS. 11-13 show a sequence of partially broken, sideelevational views of the chain capture assembly 112 and the chain 114while the chain release handle 904 is in the locked configuration, theunlocked configuration, and the open configuration, respectively.

In the locked configuration (FIG. 11), the secondary elongate member 902occupies the respective angled projections 940 of the first and secondshaped guide slots 934, 936, and the release handle 904 sits flush(i.e., vertically) in the frame 102. In this configuration, the releasehandle 904 may not be pivoted relative to the frame 102. At the sametime, a first abutment surface 962 of the first rotatable member 916abuts a first landing surface 964 of the chain capture block 926, whilea second abutment surface 966 of the second rotatable member 918 abuts asecond landing surface 968 of the chain capture block 926. The first andsecond rotatable members 916, 918 thereby hold the chain capture block926 in a fixed orientation in the frame 102 with the mouth of the cavity956 angled somewhat upward. This orientation of the chain capture block926 is hereinafter called the “chain capture orientation.”

A user may insert the chain 114 into the chain capture block 926 whilethe release handle 904 is in the locked configuration and the chaincapture block 926 is in the chain capture orientation simply byinserting two links of the chain 114 into the cavity 956 of the chaincapture block 926 while the chain 114 is not under tension. In makingthis insertion, the vertically oriented link of the two chain links willpress against a projection 970 on the chain keeper member 920, but thechain keeper member 920 will pivot out of the way so that the verticallink can pass unimpeded. After the vertical chain link passes, the chainkeeper member 920 will snap back into position in response to the biasof the coil spring 922.

In contrast, once the chain links of the chain 114 are inserted into thecavity 956 of the chain capture block 926 (FIG. 11), the projection 970of the chain keeper member 920 will interfere with the removal of thoselinks from the chain capture block 926. More particularly, tabs 972 onthe chain keeper member 920 will interact with the third elongate member924 to stop the chain keeper member 920 from pivoting in the requireddirection for the chain 114 to be removed. The chain keeper member 920therefore allows easy insertion of the chain 114 into the chain captureblock 926, but interferes with the removal of the chain 114 once soinserted. The chances of the chain 114 inadvertently falling out of thechain capture block 926 are thereby mitigated.

Once the chain 114 is inserted into the chain capture block 926 andunder tension, the chain capture block 926 in cooperation with theremainder of the chain capture assembly 112 will securely capture thechain 114. This configuration will be maintained until a user chooses tointentionally release the chain 114. To release the chain 114 requiresthat two distinct forces be applied to the release handle 904.

The first step in releasing the chain 114 is shown in FIG. 12, whichshows the release handle 904 after it has been translated from thelocked configuration into the unlocked configuration. To achieve thisunlocked configuration, the release handle 904 is translated relative tothe frame 102 upward away from the chain capture block 926 while theorientation of the release handle 904 relative to the frame 102 remainslargely fixed (i.e., the release handle 904 remains flush to the frame102). This upward motion occurs against the bias of the first and secondlocking springs 908, 910, thereby requiring an intentional actuation bythe user. That is, the first and second locking springs 908, 910 urgethe release handle 904 from the unlocked configuration back into thelocked configuration when the release handle 904 is translated upwardinto the unlocked configuration. Once in the unlocked state, thesecondary elongate member 902 has moved from the respective angledprojections 940 of the first and second shaped guide slots 934, 936 intotheir respective arcs 938. The release handle 904 therefore is no longerrestricted from pivoting, as was the case in the locked configuration(FIG. 11). Nevertheless, as long as the release handle 904 stays flushto the frame 102, the chain capture block 926 remains restricted in itsability to pivot in the frame 102, and the chain 114 remains secured.

Subsequently, in a second separate, positive motion, the release handle904 may be pivoted relative to the frame 102 to achieve the openconfiguration in FIG. 13. In the open configuration, the first andsecond abutment surfaces 962, 966 of the first and second rotatablemembers 916, 918 disengage from the first and second landing surfaces964, 968 of the chain capture block 926, allowing the chain captureblock 926 to now freely pivot within the frame 102. As shown in FIG. 13,the chain capture block 926 pivots in the frame 102 to a “chain releaseorientation.” The chain 114 is thereby allowed to fall away from thechain capture assembly 112 and, more generally, the apparatus 100.

Subsequently, to place the apparatus 100 in condition to again receivethe chain 114, the chain capture block 926 is returned to the chaincapture orientation and the release handle 904 is pivoted back into itsunlocked configuration flush to the frame 102 (FIG. 12). Thereafter, therelease handle 904 is allowed to translate downward into the lockedconfiguration (FIG. 11).

To summarize, the chain capture block 926 is operative to achieve achain capture orientation and a chain release orientation relative tothe frame 102. The first and second shaped guide slots 934, 936 in therelease handle 904 cooperate with the secondary elongate member 902 toallow the release handle 904 to be translated relative to the frame 102between the locked configuration and the unlocked configuration. At thesame time, the first and second shaped guide slots 934, 936 furthercooperate with the secondary elongate member 902 to allow the releasehandle 904 to be pivoted relative to frame 102 between the unlockedconfiguration and the open configuration. With the release handle 904 inthe locked and unlocked configurations, the first and second rotatablemembers 916, 918 interfere with the pivoting of the chain capture block926 from the chain capture orientation to the chain release orientation.With the release handle 904 in the open configuration, the chain captureblock 926 is free to pivot between the chain capture orientation and thechain release orientation.

Configured in the manner set forth above, the chain capture assembly 112requires that two distinct forces be applied to the release handle 904in order to release the chain 114. Prior art assemblies, in contrast,have typically required only a single motion of a release handle torelease a chain, making these prior art assemblies more prone toinadvertent releases. Advantageously, the two separate forces requiredto release the chain capture assembly 112 (i.e., first the upwardtranslation of the release handle 904, and then the pivoting of therelease handle 904 away from the frame 102) are in two almost oppositedirections. Inadvertent releases are therefore extremely unlikely whenutilizing the chain capture assembly 112, and more generally,embodiments in accordance with aspects of the invention.

Once understood from the details provided herein, the elements of thechain capture assembly 112 may be formed utilizing conventionalmanufacturing techniques or, in the case of fasteners, springs, and thelike, sourced commercially. For strength, most of the elements of theapparatus 100 preferably comprise a metal such as, but not limited, tosteel. Metal machining is described in W. A. Knight et al., Fundamentalsof Metal Machining and Machine Tools, Third Edition (cited earlier).

Like the hook assembly 104, the chain capture assembly 112 lends itselfto several modifications. As just one example, the particular fastenersand types of springs utilized in the embodiment set forth above may bereplaced by equally suitable fasteners and biasing elements, and theresults would still come within the scope of the invention. As anotherexample, embodiments in accordance with aspects of the invention mayutilize only a single rotatable member (instead of a pair of rotatablemembers) to obtain the desired functionality. These numerous alternativeembodiments will be apparent to one skilled in the art given theteachings herein.

All the features disclosed herein may be replaced by alternativefeatures serving the same, equivalent, or similar purposes, unlessexpressly stated otherwise. Thus, unless expressly stated otherwise,each feature disclosed is one example only of a generic series ofequivalent or similar features.

Any element in a claim that does not explicitly state “means for”performing a specified function or “step for” performing a specifiedfunction is not to be interpreted as a “means for” or “step for” clauseas specified in AIA 35 U.S.C. §112(f). In particular, the use of “stepof” in the claims herein is not intended to invoke the provisions of AIA35 U.S.C. §112(f).

What is claimed is:
 1. An apparatus comprising: a frame; a locking body,the locking body fixed in the frame, and defining a cavity and anaperture therein, the aperture being in communication with the cavity; athreaded receiver, the threaded receiver passing through the aperture,at least partially occupying the cavity, and free to rotate; a lockingplate, the locking plate defining a mating slot and having a shape thatprevents the locking plate from rotating within the cavity when thelocking plate is inserted into the cavity; a biasing element, thebiasing element in contact with the locking plate; an attachmentelement; and a threaded shaft, the threaded shaft extending in alongitudinal direction from the attachment element through the threadedreceiver and the mating slot, and shaped so as to cooperate with themating slot to prevent the threaded shaft from rotating independently ofthe locking plate while still being translatable in the longitudinaldirection therethrough; wherein the apparatus is operative to take on aplurality of locked states and an unlocked state, each of the pluralityof locked states characterized by the locking plate being pressed intothe cavity by the biasing element and thereby prevented from rotating bythe locking body, and the unlocked state characterized by the lockingplate being outside the cavity and thereby free to rotate; wherein theunlocked state can be achieved from a respective one of the plurality oflocked states by manually pressing the threaded receiver against thelocking plate so as to translate the locking plate out of the cavitycounter to the bias of the biasing element.
 2. The apparatus of claim 1,wherein the threaded receiver comprises a protruding lip, the protrudinglip occupying the cavity and abutting a perimeter of the aperture insidethe cavity when the apparatus is in one of the plurality of lockedstates.
 3. The apparatus of claim 2, wherein the protruding lip is inspaced relation to the perimeter of the aperture when the apparatus isin the unlocked state.
 4. The apparatus of claim 3, wherein the biasingelement presses the locking plate against the threaded receiver.
 5. Theapparatus of claim 1, wherein the locking plate defines a pair ofparallel outside edges.
 6. The apparatus of claim 5, wherein the lockingbody defines a pair of parallel internal sidewalls spaced apart by adistance about equal to a space between the pair of parallel outsideedges.
 7. The apparatus of claim 1, wherein a portion of the threadedshaft is defined by an externally threaded cylinder with a pair ofoppositely facing flat surfaces.
 8. The apparatus of claim 7, whereinthe mating slot is characterized by a pair of opposed sidewalls spacedapart by a distance about equal to a spacing between the pair ofoppositely facing flat surfaces.
 9. The apparatus of claim 7, whereinthe mating slot is characterized by a pair of opposite sidewalls spacedapart by a distance greater than a maximum diameter of the externallythreaded cylinder.
 10. The apparatus of claim 1, wherein the biasingelement comprises a spring.
 11. The apparatus of claim 10, wherein thespring comprises a leaf spring.
 12. The apparatus of claim 1, whereinthe attachment element comprises a hook.
 13. The apparatus of claim 12,wherein the hook comprises a spring-loaded keeper.
 14. The apparatus ofclaim 1, further comprising a tensioning wheel, the tensioning wheelrotatably and translatably coupled to the threaded receiver.
 15. Theapparatus of claim 1, wherein the apparatus is adapted to be releasablyattached to a chain.
 16. The apparatus of claim 1, wherein rotating thethreaded receiver with the apparatus in the locked state causes theattachment element to move in the longitudinal direction relative to theframe while maintaining a fixed orientation relative to the frame. 17.The apparatus of claim 1, wherein the attachment element is operative totake on four different locked states, each of the four locked statescharacterized by a different orientation of the attachment elementrelative to the frame.
 18. The apparatus of claim 1, wherein theattachment element is operative to take on more than four differentlocked states, each of the more than four locked states characterized bya different orientation of the attachment element relative to the frame.